Centrifugal drive means for missile and fuze applications



Dec. 19, 1961 .G. WENIG 3,013,496

CENTRIFUGA RIVE MEANS F0 ISSILE AND FUZE LICATIO Filed Se 2, 1960 3,013,496 CENTRIFUGAL DRIVE MEANS FOR MISSILE AND FUZE APPLICATIONS Harold G. Wenig, Brooklyn, N.Y., assignor to the United States of America as represented by the Secretary of the Army Filed Sept. 2, 1960, Ser. No. 53,857 3 Claims. (Cl. 10280) This invention relates to centrifugal drive means for missile and fuze applications and more particularly to means for rotating a rotor in a missile or fuze utilizing centrifugal force applied to a spring by rotation of the device.

The invention comprises a centrifugal spring arrangement in a fuze or missile which under certain conditions will act as a safety spring to keep a rotor in the unarmed or zero position and under other conditions will act as a torque drive to move the rotor to armed or controlling position. The spring, which may take a number of forms such as spiral, helical or other suitable shape, has one end attached to a stator which is fixed to the fuze or missile body. The other end of the spring is attached to the rotor which is rotatably mounted with respect to the stator. In fuze applications the rotor carries a pyrotechnic element which is rotatable through 90 to an armed position while in missile applications the rotor carries contact elements which provide signals in accordance with the speed of rotation of the missile.

Before the fuze or missile body is spinning, i.e., before it is fired, the centrifugal spring will keep the rotor in the unarmed or zero position which is the equilibrium position of the spring. The spring is made stiff enough to prevent the rotor from rotating to armed position accidentally during handling. When the fuze or missile acquires a high spin velocity in flight, centrifugal force acts on each element of the spring causing the spring to expand or deform. As the spring expands or deforms, the end which is attached to the rotor exerts a torque on the rotor and moves the rotor. In fuze applications the spring is so designed as to move the rotor 90 to the armed position. In missile applications the spring is so designed as to move the rotor in accordance with the amount of spin to provide a control signal to the missile.

It is an object of this invention to provide a fuze which is armed in flight by a centrifugal spring arrangement.

It is another object to provide a fun which is safe to handle, is positively armed in flight and yet is extremely simple in construction.

Another object of the invention is to provide a missile with a centrifugal spring arrangement to provide a signal in accordance with the rotational velocity of the missile.

Yet another object is to provide a fuze having a stator and rotor held in unarmed position by a spring in equilibrium and moved to armed position by centrifugal force acting on the spring.

Still another object is to provide a projectile with a rotor which is rotated in flight by the torque of a spring which results from centrifugal force acting on the spring.

These and other objects will become more apparent when reference is had to the following detailed description and drawing in which like reference characters are used to designate the same or corresponding par-ts throughout the figures.

In the drawing:

FIGURE 1 shows a fuze partly in section illustrating one embodiment of the present invention,

FIGURE 2 is a cross-sectional view of the embodiment of FIGURE 1 taken on the line 22 thereof and looking in the direction of the arrows, but with the rotor moved to armed position,

FIGURE 3 is a view partly in section of a different Stes Patet O 3,013,496 Patented Dec. 19, 1961 ice embodiment of the invention as applied to a guided missile,

FIGURE 4 is a cross-sectional view of the embodiment shown in FIGURE 3 taken on the line 4-4 thereof and looking in the direction of the arrows,

FIGURE 5 is a partial sectional view of another embodiment of a fuze according to this invention, and

FIGURE 6 is a cross-sectional view of the embodiment shown in FIGURE 5 taken on the line 6-6 thereof and looking in the direction of the arrows.

Referring now specifically to the embodiment illustrated in FIGURES 1 and 2 there is shown a fuze adapted for attachment to a spin stabilized projectile. The fuze has the body 1 with reduced, rearwardly extending, threaded portion 2 and base portion 3. The body 1 is provided with the axial bore 4 and has rigidly attached thereto the stator element 5 which is received in the bore. The base member 3 and stator 5 have aligned recesses 6 and 7, respectively. A rotor 8 is provided which has the extended spindle portions 9 received in the recesses 6 and 7 to rotatably support the rotor within the body 1. The base 3 is further provided with a recess 10 in which is slidably received a set back pin 11. This pin is received in recess 12 in the rotor 8 as shown in FIGURE 1 when the fuze is in unarmed condition and the pin remains in the position shown due to a friction fit in recess 10. The base plate 3 is also provided with a through passage which receives the pyrotechnic element 13, while the rotor 8 is provided with the pyrotechnic element 14. The

stator element 5 carries the firing pin 15 which alignswith the pyrotechnic element 13. The periphery of the rotor 8 is provided with a groove 16 of substantial circumferential extent and the housing 1 is provided with the projecting pin 17 which engages with the end of the coil form, but may be spiral or other suitableshape.

When the fuze is in the safe or unarmed position as shown in FIGURE 1 the spring 19 is in equilibrium and provides no biasing force on the rotor.

The operation of the device of FIGURES l and 2 should now be apparent. When the projectile to which the fuze is connected is fired, set back forces cause the pin 11 to overcome the frictional resistance to movement and the pin moves rearwardly in recess 10 to free the rotor. This pin is used in order to prevent distortion of the spring 19 due to rapid initial angular acceleration of the projectile. By the time the pin 11 has moved rearwardly this angular acceleration has dropped to a safe value. When the rotor 8 is in the initial unarmed position the pin 17 is received in the intermediate area of the groove 16 and oifers no resistance to movement of the rotor in either direction. The spring 19 before firing is in the equilibrium or unstressed condition. However, upon firing, rotation of the fuze and projectile causes centrifugal forces to act on each element of the spring causing the spring to expand and deform outwardly. As the spring expands the end which is attached to the rotor exerts a torque on the rotor to move it to the position shown in FIGURE 2 at which time the pin 17 engages the end of the groove 16 and prevents further rotation of the rotor. The firing pin 15 and pyrotechnic elements 14 and 13 are now aligned and the firing pin is drivenrearwardly on impact by any conventional means such as crushing of the ogive 18. The spring 19 is so designed that at the specified speed of rotation at which arming is to take place, it will exert enough torque to hold the rotor in the armed position. The time required for the rotor to move 90 from the unarmed to the armed position is dependent on the torque exerted by the spring. The torque is a function of the spin speed of the fuze, configuration and number of coils of the spring, and size and material of the. spring wire. There, by adjusting these variables the time required for the rotor to move 90 before arming may be used as an arming delay. It will be seen that the fuze is extremely safe to handle. The set-back pin 11 acts to hold the rotor against accidental displacement and even if this pin is accidentally moved rearwardly to free the rotor the spring 19 is strong enough to prevent 90 rotation of the rotor due to handling or dropping of the fuze.

The embodiment shown in FIGURES 3 and 4 illustrates the invention as applied to a guided missile and forming a part of the control thereof. The rotor, stator, centrifugal spring, and set-back pin arrangement is the same as in the embodiment of FIGURES 1 and 2 and the parts are numbered in like manner. The base portion 3 of the housing 1 is provided with a series of spaced insulator sleeves 20 which carry contact pins 2125. The rotor 8 carries the headed wiper 26 which contacts pin 21 when the spring 19 is in equilibrium position; i.e. when the missile is not spinning. As the missile spins thetcentrifugal force acting on each element of the spring 19 causes the rotor to turn an amount depending on the speed of rotation and causes the Wiper 26 to contact one of the pins 2225. An electrical circuit is formed from a source of energy in the missile through the housing 1, rotor spindle 9, rotor 8, Wiper 26 and one of the pins 2125 back to a mechanism to be controlled. Obviously the path of the signal will depend upon which pin 21-25 is contacted by the wiper 26 and a control signal is provided for the missile which is a function of the rotational speed. This signal can be utilized to control the speed of rotation of the missile. As shown in FIGURE 3 the wiper is in contact with pin 25 which is a position of high spin velocity.

FIGURES and 6 illustrate a third embodiment of the invention in which the set-back pin 11 is dispensed with. The centrifugally operated spring 19 in this embodiment is disposed between the rotor 8 and housing base portion 3 and the base portion 3 thus acts as the stator. The housing 1 is provided with the inwardly projecting pin 27 and the rotor is provided with the circumferential slot 28 of 90 arcuate extent and having opposite end walls 29 and 30. The rotor as shown in FIGURE 5 is in the unarmed position with the spring 19 unstressed and the pin 27 in engagement with the end wall 29 of the slot 28. Upon firing, the high angular acceleration to which the fuze is subjected would deform the spring 19 were it not for the pin 27 and groove 28. During this angular acceleration the pin 27 presses against the end wall 29 of the groove and accelerates the rotor 8 with the housing 1 and base or stator portion 3. When the angular acceleration'drops or ceases centrifugal force acting on the elements of the spring 19 will rotate the rotor clockwise as viewed from the rear to the armed position shown in FIGURE 6. When the rotor has rotated through the pin 27 will engage with the groove end wall 30 and the pyrotechnic elements 13 and 14 will be aligned. Continued spin of the projectile holds the rotor in armed position until the target is met to operate the firing pin 15. It will be noted that when used as an anti-aircraft projectile the spring 19 may be so selected that if the projectile misses the target the spring may cause the rotor to retrogress upon stagnation of spin and again become unarmed. In this manner the projectile would not explode upon striking the ground. The spring 19 is made stiff enough so as to prevent displacement of the rotor 8 through 90 during handling.

While I have disclosed a number of forms of my invention it will be obvious that various changes may be made in construction and arrangement without departing from the scope of my invention as defined by the subjoined claims.

I claim:

1. A fuze comprising a body having an ogival nose portion and a reduced, externally threaded base for attachment of said fuze to a projectile, there being an axial bore in said body, a stator in said bore and spaced from said base, a firing pin in said stator, a rotor journaled axially between said base and said stator, said rotor rotating between an unarmed position and an armed position, a first pyrotechnic element in said base, a second pyrotechnic element in said rotor, 21 spiraled spring mounted coaxially in said bore, said spring exerting a torque on said rotor to rotate it into the armed position upon centrifugal force whereby said second pyrotechnic element is aligned with said first pyrotechnic element and said firing pin, means in frictional engagement with said base and said rotor and responsive to acceleration force of the projectile to free said rotor for rotation towards the armed position and means carried by said body and said rotor for limiting rotation of said rotor in its travel from the unarmed to armed positions in said body.

2. A fuze as set forth in claim 1 wherein said means in frictional engagement with said base and said rotor comprises a first recess in said base, a second recess in said rotor, said second recess being in alignment with said first recess when said rotor is in its unarmed position, and a pin frictionally fitted in the forwardportion of said first recess and extending into said second recess, said pin being forced towards the rearward portion of said first recess upon acceleration force to move out of said second recess and free said rotor for rotation toward the armed position.

3. A fuze as set forth in claim 1 wherein said means carried by said body and said rotor for limiting its rotation comprises a groove in the outer peripheral surface of said rotor and a pin fixed in said body and protruding into said groove, said groove being of sufiicient length whereby said rotor will rotate only from its unarmed position to its armed position. 7

References Cited in the file of this patent UNITED STATES PATENTS 1,726,325 Varaud Aug. 27, 1929 2,663,260 Thompson Dec. 22, 1953 2,950,367 McCathron Aug. 23, 1960 2,960,327 Gaubatz Nov. 15, 1960 

